"use strict";
  
  const DOMException = require("domexception/webidl2js-wrapper");
  const StorageEvent = require("../generated/StorageEvent");
  const idlUtils = require("../generated/utils");
  const { fireAnEvent } = require("../helpers/events");
  
  // https://html.spec.whatwg.org/multipage/webstorage.html#the-storage-interface
  class StorageImpl {
    constructor(globalObject, args, privateData) {
      const { associatedWindow, storageArea, url, type, storageQuota } = privateData;
  
      this._associatedWindow = associatedWindow;
      this._items = storageArea;
      this._url = url;
      this._type = type;
      this._quota = storageQuota;
  
      this._globalObject = globalObject;
    }
  
    _dispatchStorageEvent(key, oldValue, newValue) {
      return this._associatedWindow._currentOriginData.windowsInSameOrigin
        .filter(target => target !== this._associatedWindow)
        .forEach(target => fireAnEvent("storage", target, StorageEvent, {
          key,
          oldValue,
          newValue,
          url: this._url,
          storageArea: target["_" + this._type]
        }));
    }
  
    get length() {
      return this._items.size;
    }
  
    key(n) {
      if (n >= this._items.size) {
        return null;
      }
      return [...this._items.keys()][n];
    }
  
    getItem(key) {
      if (this._items.has(key)) {
        return this._items.get(key);
      }
      return null;
    }
  
    setItem(key, value) {
      const oldValue = this._items.get(key) || null;
  
      if (oldValue === value) {
        return;
      }
  
      // Concatenate all keys and values to measure their length against the quota
      let itemsTotalLength = key.length + value.length;
      for (const [curKey, curValue] of this._items) {
        // If the key already exists, skip it as it will be set to the new value instead
        if (key !== curKey) {
          itemsTotalLength += curKey.length + curValue.length;
        }
      }
      if (itemsTotalLength > this._quota) {
        throw DOMException.create(this._globalObject, [
          `The ${this._quota}-code unit storage quota has been exceeded.`,
          "QuotaExceededError"
        ]);
      }
  
      setTimeout(this._dispatchStorageEvent.bind(this), 0, key, oldValue, value);
  
      this._items.set(key, value);
    }
  
    removeItem(key) {
      if (this._items.has(key)) {
        setTimeout(this._dispatchStorageEvent.bind(this), 0, key, this._items.get(key), null);
  
        this._items.delete(key);
      }
    }
  
    clear() {
      if (this._items.size > 0) {
        setTimeout(this._dispatchStorageEvent.bind(this), 0, null, null, null);
  
        this._items.clear();
      }
    }
  
    get [idlUtils.supportedPropertyNames]() {
      return this._items.keys();
    }
  }
  
  module.exports = {
    implementation: StorageImpl
  };